I. Field of the Invention
The present invention relates to a water treatment apparatus. More particularly, the present invention relates to a multi-stage water treatment apparatus. Even more particularly, the present invention relates to a multi-stage water treatment apparatus for producing potable water.
II. Prior Art
Much of the public concern about the quality of drinking water centers on how the water looks, tastes or smells. Unfortunately, water that looks, tastes and smells just fine may pose severe health hazards. For example, at least 42,000,000 Americans are exposed to dangerous amounts of lead in their drinking water. Thus, more than one hundred contaminants are now subject to water-safety regulations.
Many devices currently exist for filtering water to remove contaminants. They all work with different degrees of efficiency to eliminate undesirable particles, substances and living organisms from the water being filtered. Many of these devices, however, utilize the relatively high pressure available from the tap water supply. This necessarily rushes water through the filtering media, preventing the efficient filtering function for which the device was designed. Typically, the designer's concern for efficient filtering of the water is compromised with through put considerations.
Still other water purification systems have been developed that do not use the water pressure supplied from a tap, but utilize gravity for effecting water throughput. One such system known to applicants is sold by Water Technologies, Inc., Plymouth, Minn.
This system, particularly, includes a granulated active carbon bed and a coaxially aligned resin bed of equal cross-sectional flow area containing polystyrene beads to which are bonded iodine molecules. This resin, which is described in U.S. Pat. No. 4,238,477, has proven effective in destroying the viral, bacterial and parasitic contaminants when deposited to a bed depth sufficient to provide proper contact time between the resin and water. Although effective in practice, the foregoing system has proven to be economically expensive to produce, due to the use of excessive amounts of resin. That is, the resin bed portion of the system has been constructed oversize, relative to the life of the granulated active carbon bed, in lieu of adjusting the cartridge housing configuration.
U.S. Pat. No. 5,126,044 granted to Magnusson et alia in 1992 discloses a water purification system similar to that produced by Water Technologies, Inc. However, instead of using excessive amounts of resin, Magnusson teaches lengthening the volume of iodine purification resin material, while still maintaining proper contact time between the resin and water. In essence, by increasing the length of the filtering apparatus, the water maintained contact with the iodine impregnated resin for a longer period of time, effecting assured removal of undesired contaminants.
Other problems exist with the presently known water purification systems. First, most water, especially tap water, has trace amounts of chlorine. Chlorine inhibits the effectiveness of the iodine in the previously disclosed devices, thus, significantly shortening the life of the device. Additionally, the devices tend to be designed for removing specific contaminants from water.
Consequently, there currently exists the need for a filter that can remove a broad scope of contaminants. A filtration device which uses smaller volumes of purification media and has a longer life of usefulness is additionally needed. It is to this which the present invention is directed.